The Tamarack Label Applicator available from Tamarack Products Inc. of Wauconda, Ill. 60084 is often used to cut and apply pieces of adhesive transfer tape to a moving web of paper. The adhesive transfer tape is unwound from a roll, fed by a feed roller in a controlled proportion to paper web speed. The adhesive transfer tape is then directed via rollers onto a vacuum cylinder, which has a series of holes which apply vacuum to its surface. The vacuum holds the adhesive transfer tape to the surface of the cylinder with the adhesive side of the tape facing away from the surface of the cylinder. The vacuum cylinder is rotating such that the speed of the surface of the cylinder matches the speed of the paper web. A cutoff knife means such as a blade-equipped cylinder is positioned in relation to the vacuum cylinder so that a blade or blades mounted in the cutoff means transversely cuts through the tape riding upon the vacuum cylinder, using the vacuum cylinder as a back-up or anvil surface for the blade or blades to cut against. A piece of tape is thus transversely severed and is carried on the surface of the vacuum cylinder until it is adhesively joined to the moving web of paper. This method and apparatus for applying tape is described by DeNeui, et al, in U.S. Pat. No. 2,990,081.
A problem has been noted when utilizing the above described method and apparatus. Tears and/or tear-outs have been noted in the transversely severed edge of the adhesive transfer tape liner. Tear outs are created by intersecting tears. The tear outs are roughly triangular shaped defects in the otherwise straight cut edge. On close examination, it has been noted that the tape portion causing the tear-out is typically still attached to the preceding cut-off piece of transfer tape. The tear-out can typically be separated very easily at the cut line in spite of the fact that it appears to be torn out of the edge of the previously adjoining piece of liner. We use the terms "tear" and "tears" generally to include a variety of defects at the line of transverse severance--and specifically including "tear outs".
Earlier adhesive transfer tapes, such as those from Ludlow Corporation, located at Chicopee, Mass. 01021, sometimes exhibited the tear-out problem but generally at a tolerable level. The emergence, however, of adhesive transfer tapes with thinner liners from not only Ludlow, who switched from "50#" liner (approximately 0.0028" thick) to "42#" liner (approximately 0.0023" thick), but also United Coating Technologies, located in Plainfield, Ill 60544, whose Free Film Lite tape has a 25# liner (approximately 0.0019" thick) resulted in larger, more frequent, and (thus) more objectionable tear-outs.
The tearing problems are attributable to tension spikes caused by the transverse cutting process. Because the amount of time involved in web severance is very short, the quick increase in tension of the transfer tape web or other web during this time interval is referred to as a tension spike. Thus, a tension spike is the instantaneous change in tension that occurs incident to the act of transverse severance of the web. The invention includes a number of advantageous methods and apparatus incorporating them for ameliorating these problems.